Fluid containers



April 2, 1957 A. MATHJSEN FLUID CONTAINERS Filed Feb. 21, 1955 2 Sheets-Sheet l NIM ATTORNEY INVENTOR BY qsa April 2, 1957 Filed Feb. 21, 1955 A. MATHISEN FLUID CONTAINERS 2 Sheets-Sheet 2 INVENTOR BY ZVL hm-M...

ATTORNEY FLUID CONTAINERS Anders Mathisen, London, England, assignor of one-half to Graviner Manufacturing Company Limited, and onehalf to The Wilkinson Sword Company Limited, both of London, England, both British companies Application February 21, 1955, Serial No. 489,7llt; Claims priority, application Great Britain March 3, H54 28 Claims. (Cl. 169-28) This invention relates to fluid containers, and is in part a continuation of an application filed by me in the United States Patent Ofiice on April 6, 1954, Serial No. 421,302. The invention is particularly applicable to fluid containers adapted to contain fire or explosion suppressing or inhibiting fluid. However, the invention is not limited to containers for such use.

According to the present invention there is provided a fluid container which is of tubular shape and has its tubular wall of frangible material, said container being adapted to accommodate an explosive charge, whereby ignition of said charge shatters or bursts said wall to release the fluid contents.

The invention also provides a fluid container which is of cylindrical form and of substantially uniform crosssection, at least that wall which is a surface of revolution about the longitudinal axis of the container being composed of frangible material, said container being adapted to accommodate an explosive charge ignition of which shatters or bursts said wall to release the fluid contents.

The invention further provides a fluid container comprising a cylindrical wall of frangible material and means for supporting an explosive charge substantially in the centre of said container, whereby ignition of said charge shatters or bursts said wall and distributes the fluid content outwards in a cylindrical spray pattern which is coaxial with the axis of the container.

One or more fluid containers according to the invention, and filled with fire or explosion inhibiting fluid, may be operatively connected to fire or explosion detecting means which is arranged automatically to ignite the explosive charge to distribute the fluid contents for suppressing an explosion or extinguishing a fire.

Two possible constructions of fluid container in accordance with the invention and designed to contain fire or explosion suppressing fluid, will now be described by way of example only, reference being made to the accompanying drawings, in which:

Figure 1 is a sectional side elevation through the first construction of container and through an associated terminal block and electrical shorting plate, whilst Figure 2 is a sectional view taken along the lines II-II in Figure 1;

Figure 3 shows the mounting of two containers and their associated equipment in an aircraft fuel tank, whilst Figures 4A and 4B are respectively a side elevation and a sectional view of a modified form of the first construction;

Figure 5 is a sectional side elevation through the second construction of container.

In the construction shown in Figures 1 and 2 the fluid container comprises a thin outer tube of metal provided at each end with metal fixing flanges 11a, 11b and closed by metal end plates 12a, 12b. A relatively small diameter inner tube 13, also of metal, is mounted at each end in a central aperture provided in each end plate 12a, 12b. Fitting closely within the metal inner tube 13 is a Y nited States Patent Patented Apr. 2, 1957 removable sleeve E4 of reinforced plastic material, which carries a metal socket 15 at one end and a metal plug 16 at the other. The plug 16 and socket 15 are supported by spider members 17a, Iii-"b respectively and are electrically connected by a metal foil 18 secured to the plastic inner sleeve 14. The plug 16 and socket id are each designed respectively to engage sockets and plugs of corresponding dimensions as will be further explained below. Housed within the plastic sleeve lid with its active end lying approximately midway along the length thereof is an electrically ignitable detonator 19 or other suitable explosive charge. The remaining space within the plastic sleeve 14 may be packed with a cold setting synthetic resin plastic. One end of the igniting wire of the detonator 19 is connected to the plug 16, whilst the other is connected to an earthing pin 29 supported by a moulding 21, the moulding being secured on the adjacent end of the plastic sleeve 14 which projects somewhat from the end plate 12a for this purpose. The earthing pin 20 engages in a metal socket 22 secured in the end plate 12a, the end plates 12a, 32b, flanges 11a, 11b and outer tube 10 all being at earth potential. A filler plug 23 is also provided in one end piate. In a modification not illustrated, the filler plug 23 is bored to form a socket for the earthing pin 2i), so avoiding the necessity for providing a special socket. To support the end pieces after operation of the container a plurality of struts 24, in this case three, are symmetrically positioned about the central tube 13 and are secured at each end in the end plates 12a, 12b.

The container is designed to be used with a terminal block 25 which is bolted to the end flange lla as shown in Fig. 3, the terminal block 25 being provided with a centrally positioned connector 26 providing a socket 26a on one face of the block and a projecting pin 265 on the other face. The block 25 is of insulating material and the outer upstanding portion on one face is covered with a copper stamping 27 which bears against the flange plate 11a. The stamping 27 is also formed with tag 27a which is carried round the side of the block 25 and is secured under a co-axial socket 28 mounted on the side of the block. In this way the outer conductor of the socket 28, which is maintained at earth potential through the cable normally connected to it, is electrical- 13 connected to the stamping 27 to provide an earth connection to the flange 11a and thence to all the metallic parts of the container electrically connected with the flange 11a. The inner conductor 23:: of the socket 2% is connected by a wire 29 to the connector 26. Where it is desired to make parallel connections to the terminal block 25, a second co-axial socket may be provided on the side of the block, a second tag from the stamping 27 being secured thereunder.

As shown in Fig. 3, the outer tube lid is provided with a number of longitudinal scores or grooves Illa, eight in the construction illustrated, together with a central peripheral score or groove 1% so that upon ignition of the detonator 19, which shatters the inner tube 13 and sleeve 14, the outer tube 10 is burst and tears at the grooves 10a, ltib so that the panels between the grooves are peeled back towards the end plates 12a, 12b respectively, as indicated in broken lines in Fig. l, to allow free distribution of the fluid contents which is propelled radially outwards by the explosive force at an initial speed of the order of 10d or more feet per second. The panels are retained due to their being secured between an end plate and an end flange 11a, 1211 or lib, 1%, Whilst the struts 24 retain the end members approxi mately in position even though the struts themselves may be somewhat buckled.

For certain applications the container may be mounted cantilever fashion by securing the terminal block 25 to a suitable supporting structure, for example the wall of a fuel tank. The terminal block co-axial socket 28 will receive the plug of a lead by which igniting current is fed to the detonator. Ignition may be eifected by manual closure of a switch, or automatically by explosion or fire detection means.

A single container mounted cantilever fashion is particularly suitable for explosion suppression in shallow fuel tanks, such as the saddle tanks used in some aircraft, but for deeper fuel tanks, or in cases where it is more convenient for the tubes to be mounted along the length of a shallow tank, several containers may be mounted endto-end. Dependent upon the size of the tank a plurality of stacks of containers may be used appropriately positioned relative to one another. The containers are secured together by the flange plates 11a, 11b with the plug 16 of one engaged in the socket of the next. The containers will then have their detonators 19 connected electrically in parallel.

The arrangement will be similar to that shown in Figure 3, except that in this figure the two containers are spaced apart by a dummy container 29 to be referred to in greater detail below. To ensure that as many as possible of the containers will operate even if the electrical circuit of an intermediate container is broken, a terminal block may be provided at each end as shown in Figure 3 to provide a ring circuit through the containers. To enable containers of standard length to be used in diiferent installations an adaptor sleeve 30 of suitable length may be used at one end of the stack of containers. This adaptor may take the form of two tubes telescoped together and each provided with one end flange at opposite ends to one another so that the sleeve can be extended to the required extent and the tubes then fixed together, for example by bolting, in the required position to provide a sleeve of appropriate length.

A dummy container is used where the length of a stack of containers would otherwise be such that more suppressant than necessary would be provided. The function of a dummy container is to serve as a spacer and support and to provide the electrical interconnections. Thus a dummy container need not be provided with a detonator nor need the outer tube be scored. Naturally it will not contain suppressant and holes may be formed in the outer tube to allow fuel to enter. Where the limitation on firing current requires a stack of containers to be electrically connected in series one lead of the detonator will be connected to the plug carried by the inner sleeve and the other lead will be connected to the socket at the opposite end of the sleeve. A metal shorting plate 31 (Fig. 1) is then provided at the opposite end of the stack to the terminal block, this shorting plate 31 having a pin 31a which engages the socket 15 in the end container whilst the plate is bolted to the flange 11b to provide the earth return connection.

Fig. 3 also shows one method of mounting a stack of containers in an aircraft fuel tank of the rubber bag type. Each end of the stack is bolted to a metal spider 32 which is in turn secured to the bag tank wall 33 by a fixing member 34 of known kind designed for this purpose. A rubber backing pad 35 is mounted at each end of the stack to bear on the wall 33. The fact that a stack of containers only requires support at one or both ends results in a relatively simple installation.

A suitable material for the outer tube 10, the end flanges 11a, 11b and the end plates 12a, 12b is a stainless steel, copper, or an alloy of copper, aluminium and zinc known as Tungum, although other metals may be used provided that the material used for the outer tube is ductile where tearing, as opposed to shattering, is required. The end plates and flanges may, for example, be made of titanium or an alloy thereof in order to have minimum weight for a given strength.

By way of example only, it maybe stated that one form of container has been made in 'which'the outer tube is approximately four inches long and two inches in diameter and is provided with eight longitudinal grooves of an approximate depth of 0.007 of an inch formed in a stainless steel wall of 0.015 of an inch thickness. Using "Tungum," the tubing had a wall thickness of 0.022 of an inch. The longitudinal grooves may conveniently be formed during the manufacture of long lengths of the tube and prior to its parting-oflf into the required lengths. Peeling back of the scored panels whilst still retaining them between the end plates and flanges so that they do not fly oif as large fragments, may be facilitated by forming the longitudinal grooves so that their depth increases progressively from adjacent each end of the container to their junction with the peripheral groove.

The eifective spray pattern produced upon discharge extends in all directions radially outwards from the container and roughly covers a cylinder coaxial with the container and of approximately twice the length of the outer tube, that is to say suppressant is distributed backwards past each end flange.

In some circumstances a directional spray pattern may be required, for example where a tank is to be protected which is so shaped that instead of an all-round spray pattern discharge is required over a narrow segment only. One method of achieving a directional spray pattern is to construct the outer tube so that it is of varying strength and only part of it is burst, the remainder either not being burst or at least not being peeled back substantially. Alternatively, the tube may be made of varying strength by provision of score lines on part only of its periphery.

Rather than having a single outer tube it may be more simple for ease of manufacture to have a composite outer tube of two members fitting one within the other, the outer sleeve being relatively non-frangible and suitably shaped. One such construction is shown in Figures 4A and 48 where the frangible tube 10 is enclosed by a relatively non-frangible sleeve 36. The sleeve 36 is provided with one or more apertures; in the construction shown two such apertures 36a are illustrated. The sleeve 36 reinforces the frangible tube 10 so that upon ignition of the explosive charge the tube 10 is only burst fully open at the portion of its outer surface which coincides with the apertures 360, the remainder of the tube 10' and the sleeve 36 not being burst wide open although they may be deformed to some extent. To assist in full opening of the desired portion of the tube 10' this may be scored, for example as indicated by the score lines 10a and 10b, Figure 4B indicating how the petal portions opened, these petal portions finally coming to rest against the outside of the sleeve 36. In this way the discharge pattern is in the form of a relatively narrow segment. It will 'be understood that the aperture or apertures formed in the sleeve 36 may be so chosen as to give varying directional discharge patterns, and they may extend continuously from one end to the other of the tube and be of various peripheral widths. Moreover, the sleeve need not be in contact with the tube but may be spaced some distance therefrom in which case it will serve as a reflector rather than as a means for preventing or limiting the extent of bursting of the tube. For standardisation'of production the sleeve may be so mounted that it can be rotated relative to the'tube during installation.

It will be apparent that many modifications are possible in the above described construction of fluid container, and Fig. 4 shows one possible alternative construction, in which the outer tube is shattered into'fragments and not burst as in the previous construction. As shown in Fig. 4 the container comprises a tube 40 of frangible material, for example resin-bonded fibre, each endof which is closed bya plug 41a, 41b which serves to support a. detonator' 42a, 42b lying along the axis of the tube 40. The position of each detonator 42a, 42b is such that its explosive portion -lies 'approximately midway between the inner' end of its supporting plug 41a, 41b and the centre of the container.

Two wire conductors 43 serving as electrical bus bars extend throughout the length of the container, and at the end plug die the conductors 43 terminate in sockets 44 whilst at the other end plug 41b they terminate in projecting pins 45. At this latter end, an internally-threaded captive connecting ring 46 is provided, the plug 41a being provided with an external screw-thread dial which is adapted to receive the connecting ring 46 of an associated container. In this way a plurality of suppressant corn tainers can be connected together end-to-end by insertion of the pins 45 of one into the corresponding sockets 44 of the next container, the containers being thereafter secured together by screwing-up of the connecting rings 46 to give a long cylindrical tube. The igniting wires 42a1, 42b1 of the detonators are connected to the respective bus bars 43 so that when an energising circuit is connected to one or both ends of the stack of suppres sant containers, all the igniting circuits are electrically in parallel. When the detonators 42a, 4211 are ignited, substantially the whole of the tube 4t) is shattered and the liquid is projected outwards in a cylindrical spray pattern co-axial with the axis of the container.

Whilst the tube may be of any frangible material compatible with the particular liquid to beused, and which is of a form which is shattered by ignition of the detonators, one suitable material for this purpose is resinbonded fibre of the kind sold under the registered trade mark as Tufnol.

Of course, where the container is used in an aircraft fuel tank the fragments must be such as to avoid blockage of the fuel system or damage to the power plants. Where suitable, the use of translucent material facilitates checking of the content. As before, the tube may be formed with lines of Weakness to facilitate fracture along predetermined lines.

By way of example only, it may be stated that such containers have been constructed which were one foot in length between end plugs, and of between one inch and two inches in internal diameter, the smaller diameter tubing containing approximately 125 cos. of suppressant whilst the larger diameter contained approximately 500 ccs.

Apart from the use of detonators, other forms of explosive charge may be used. One alternative is to use an explosive in cord form, in which case the cord will extend continuously between the two ends of the complete container, spacers being provided at suitable distances along the tube to support the explosive charge. Ignition of the cord is effected by a small detonator or matchhead fuse.

In such a construction it may be preferable to provide a single length of tube cut to suit the length of the tank, and avoid the necessity for connecting up a number of unit containers. On the other hand, the advantage of unit containers lies in the possible standardisation of production and simplification of stores holdings. Whilst only straight containers have been mentioned, it will be understood that Where the space to be protected requires it, curved containers may be used. They may also be made flexible by using flexible tubing, for example of polyvinyl chloride, for the container body.

Where it is desired to use a non-metallic material for the tube, but the material is pervious to the fluid contents although metal is impervious to the fluid, a thin metal liner may be used inside the non-metallic tube to prevent loss of fluid.

What I claim is:

l. A fluid container comprising a frangible tubular envelope, two non-frangible closure members, each of said non-frangible closure members being sealed across one end of said envelope respectively, a further tubular member, each end of said further tubular member being secured to one closure member respectively with said further tubular member extending centrally through the interior of saidenvelope, the space between said further tubular member and said envelope containing liquid, an explosive charge mounted within the interior of said further tubular member, said explosive charge having an electrical igniting wire, and electrical connector means at each end of said further tubular member, said igniting wire being electrically connected to each of said connector members.

2. A fluid container comprising an elongated frangible envelope, two non-frangible envelope closure members, each of said closure members closing one end of said envelope, a further elongated frangible member, said further elongated frangible member being of substantially smaller diameter than the diameter of said envelope, each end of said further elongated frangible member being secured to one closure member respectively with the further eiongated frangible member extending through the interior of said envelope, the space between said further elongated frangible member and said envelope containing liquid, and an explosive charge mounted within the interior of said further elongated frangible member to produce upon ignition an explosive force which fractures said further elongated frangible member and said envelope.

3. A fluid container comprising a frangible tubular envelope, said envelope being of substantially uniform cross-sectional dimensions throughout its length, two end caps, each end cap being sealed to said envelope adjacent one end thereof, an explosive charge, said explosive charge having electrical igniting means, and support means for supporting said explosive charge within the interior of said envelope, said envelope having a plurality of grooves in one surface extending parallel to the longitudinal axis of the envelope, said envelope also having in said one surface a groove which extends around the periphery of said envelope.

4. A fluid container comprising a ductile tubular envelope, two nou-frangible closure members, each of said non-frangible closure members being sealed across one end of said envelope respectively, a further tubular member, each end of said further tubular member being secured to one closure member respectively with said further tubular member extending centrally through the interior of said envelope, the space between said further tubular member and said envelope being substantially filled with liquid, an electrically ignitable explosive charge mounted within the interior of said further tubular member, said explosive charge having an electrical igniting wire, and electrical connector means at each end of said further tubular member, said igniting wire being electrically connected to each of said connector members.

5. A fluid container comprising a ductile tubular envelope, said envelope being of substantially uniform cross-sectional dimensions throughout its length, two end closure members, each closure member being sealed to said envelope adjacent one end thereof, said envelope having a plurality of grooves in one surface extending longitudinally between said end closure members, an electrically ignitable explosive charge, and means supporting said explosive charge within the interior of said envelope to produce upon ignition an explosive force which ruptures said ductile envelope.

6. A fluid container according to claim 5, in which the thickness of an ungrooved portion of the envelope is approximately twice the thickness at a grooved portion of the envelope.

7. A fluid container according to claim 5, in which the depth of said grooves increases progressively from adjacent each end ofthe envelope to a point approximately midway along the length of the envelope.

8. A fluid container comprising a ductile tubular envelope, two non-frangible envelope closure members, each of said closure members closing one end of said envelope, a further tubular member, said further tubular member being frangible and being of substantially smaller diameter than the diameter of said envelope, each end of said further tubular member being secured to one closure member respectively with the further tubular member extending through the interior of said envelope, and an explosive charge mounted within the interior of said further tubular member to produce upon ignition an explosive force which fractures said further tubular member and said ductile envelope.

9. A fluid container according to claim 8, in which said envelope is composed of stainless steel.

10. A fluid container according to claim 8, in which said envelope is composed of a metal selected from the group consisting of copper and copper alloys.

11. A fluid container comprising a frangible tubular envelope, said envelope being of circular cross-section, two non-frangible closure members, each of said non-frangible closure members being sealed across one end of said envelope respectively, a further frangible tubular member of circular cross-section, the diameter of said further tubular member being substantially smaller than that of said envelope, each end of said further tubular member being secured to one closure member respectively with said further tubular member extending through the interior of said envelope and being co-axial therewith, the annular space between said further tubular member and said envelope being substantially filled with liquid, an electrically ignitable explosive charge mounted within the interior of said further tubular member to produce upon ignition an explosive force which fractures said further tubular member and said envelope, said explosive charge having an electrical igniting wire, and electrical connector means at each end of said further tubular member, each end of said igniting wire being electrically connected to one of said connector members respectively.

12. A fluid container according to claim 11, in which said envelope is composed of a synthetic resin plastic material.

13. A fluid containercomprising a ductile tubular envelope, said envelope being of substantially uniform cross-sectional dimensions throughout its length, two end caps, each end cap being sealed to said envelope adjacent one end thereof, an electrically ignitable explosive charge, and support means for supporting said explosive charge within the interior of said envelope, said envelope having a plurality of grooves in one surface extending parallel to the longitudinal axis of the envelope, said envelope also having in said one surface a groove which extends around the periphery of said envelope.

14. A fluid container according to claim 13, in which the thickness of an ungrooved portion of the envelope is approximately twice the thickness at a grooved portion of the envelope.

15. A fluid container according to claim 13, in which the depth of each of said grooves increases progressively from adjacent one end of the envelope to a point approximately midway along the length of the envelope and then decreases progressively from said point to the other end of said envelope.

16. A fluid container comprising a ductile metal envelope, of cylindrical cross-section, two closure members, each of said closure members being secured across one end of said envelope respectively, a plurality of struts, each strut extending from one end cap to the other and being secured thereto, an electrically ignitable explosive charge, means for mounting said explosive charge within the interior of said envelope, said explosive charge having an electrical igniting wire for igniting said explosive charge to produce an explosive force which tears said ductile envelope, and electrical connector means mounted in each closure member, one end of said igniting wire being electrically connected to both of said connector members and the other end of said igniting wire being electrically connected to said envelope whereby a source of igniting current can be electrically connected to said envelope and said electrical connector means.

17. A fluid container according to claim 16, in which the length of said envelope is at least twice the diameter of said envelope.

18. A fluid container according to claim 16, in which said explosive charge is a fast acting detonator, said detonator being mounted with its longitudinal axis substantially coaxial with the longitudinal axis of said cylindrical envelope.

19. A fluid container according to claim 16, in which said explosive charge is of cord form.

20. A fluid container comprising a frangible envelope of cylindrical cross-section, two closure members, each or. said closure members being secured across one end of said envelope respectively, two flanged mounting members, each mounting member being secured to one end of said envelope adjacent one closure member respectively, a plurality of non-frangible struts, each strut extending from one end cap to the other and being secured thereto, an electrically ignitable explosive charge, means for mounting said explosive charge within the interior of said envelope, said explosive charge having an electrical igniting wire for igniting said explosive charge to produce an explosive force which ruptures said envelope, and two electrical connector means, one connector means being mounted in each closure member, one end of said igniting wire being electrically connected to one of said connector means and the other end of said igniting wire being electrically connected to the other of said connector means whereby an igniting circuit can be electrically connected to said igniting wire through said two connector means.

21. A fluid container comprising a ductile metal envelope of cylindrical cross-section, two non-frangible metal closure members each of said closure members being secured across one end of said envelope respectively and being electrically bonded thereto, a plurality of non-frangible struts, each end of each strut being secured in one end cap respectively, an electrically ignitable explosive charge, support means for mounting said explosive charge within the interior of said envelope, said explosive charge having an electrical igniting wire for igniting said explosive charge to produce an explosive force which tears said ductile envelope, and electrical connector means mounted in each closure member, one end of said igniting wire being electrically connected to the connector means in one closure member and the other end of said igniting wire being electrically connected to the connector means in the other closure member whereby a source of igniting current can be electrically connected through said connector means to ignite said explosive charge.

22. A fluid container according to claim 21, in which said envelope is composed of stainless steel.

23. A fluid container according to claim 21, in which said envelope is composed of a metal selected from the group consisting of copper and copper alloys.

24-. A fluid container comprising in combination a plurality of cylindrical containers secured to one another with the end of one container abutting an adjacent container, each container comprising a frangible tubular envelope, two substantially.non-frangible end caps, each end cap being sealed to one end of said envelope, and an electrically ignitable explosive charge mounted within the interior of said envelope to produce upon ignition an explosive force which ruptures said envelope.

25. In combination, a plurality of cylindrical containers each comprising a frangible envelope of cylindrical cross-section, two closure members, each of said closure members being secured across one end of said envelope respectively, two flange mounting members, each mounting member being secured to one end of said envelope adjacent one closure member respectively, a plurality of non-frangible struts, each strut extending from one end cap to the other and being secured thereto, an

electrically ignitable explosive charge, means for mounting said explosive charge within the interior of said envelope, said explosive charge having an electrical igniting wire for igniting said explosive charge to produce an explosive force which ruptures said envelope, and two electrical connector means, one connector means being mounted in each closure member, one end of said igniting wire being electrically connected to one of said connector means and the other end of said igniting wire being electrically connected to the other of said connector means whereby an igniting circuit can be electrically connected to said igniting wire through said two connector means, said plurality of containers being secured with their respective flanged mounting members in abutting relationship.

26. A fluid container according to claim 21, comprising an arcuate non-frangible shield mounted adjacent said envelope, said shield resisting the explosive force whereby discharge in the direction of said shield is prevented.

27. A fluid container according to claim 21, in which different parts of said envelope have different strengths, the strength of the parts of greater strength being sulficient to resist the explosive force whereby said parts of greater strength do not burst under the explosive force.

28. A fluid container comprising a frangible tubular envelope, said envelope being of substantially uniform cross-sectional dimensions throughout its length, two end closure members, each closure member being sealed to said envelope adjacent one end thereof, said envelope having a plurality of grooves in one surface extending longitudinally between said end closure members, an explosive charge, said explosive charge having electrical igniting means, and means supporting said explosive charge within the interior of said envelope to produce upon ignition an explosive force which ruptures said envelope.

References Cited in the file of this patent UNITED STATES PATENTS 1,453,091 Delbare Apr. 24, 1923 1,708,869 Buddecke Apr. 9, 1929 2,057,840 Neumann Oct. 20, 1936 2,373,819 Eaton Apr. 17, 1945 2,450,569 Thompson Oct. 5, 1948 

